Potential Value of Urinary Exosome-Derived let-7c-5p in the Diagnosis and Progression of Type II Diabetic Nephropathy

BACKGROUND Diabetic nephropathy (DN) is a leading cause of death worldwide. Reliable biomarkers are demanded for the non-invasive diagnosis of DN. This study aims to investigate whether miRNA in urinary exosomes could serve as a potential biomarker in the diagnosis and progression of DN. METHODS Urine samples were collected from fifteen healthy controls, twenty type II diabetes without DN and twenty-eight type II patients with DN who underwent kidney biopsy. Differential centrifugation was used to isolate exosomes from urine samples and exosomes were confirmed by electron microscopy, nanoparticle tracking analysis (NTA), and western blot. MiRNAs including let-7c-5p, miR-29c-5p, miR-15b-5p, and RNU6 were detected by real-time quantitative polymerase chain reaction (RT-PCR). RESULTS Electron microscopy and NTA verified a typical shape of exosomes with an average diameter of 100.7 nm, and western blot identified the presence of CD9, Alix, and TSG101 on exosomes. let-7c-5p was significantly upregulated in urinary exosomes of DN patients compared with controls (p < 0.05), while miR-29c-5p and miR-15b-5p were significantly downregulated compared with healthy controls (p < 0.05). let-7c-5p is correlated with both estimated glomerular filtration rate (r = -0.723, p < 0.001) and progression of DN. All three miRNAs, let-7c-5p, miR29c-5p, and miR-15b-5p, could predict DN with AUC of 0.818, 0.774, and 0.818, respectively. CONCLUSIONS Urinary exosome-derived let-7c-5p is correlated with both renal function and progression of DN, suggesting it as a potential biomarker for DN.